The Washington Department of Fish and Wildlife announced that it is working with its partners and tribes to “deploy resources and get more boots in the mud” to control infestations of the invasive European green crab along the coast and certain sites within the Salish Sea.
Officials said the crabs pose a threat to the state’s economic, environmental and cultural resources. The crabs “are a globally damaging invasive species.”
“Potential impacts include destruction of eelgrass beds and estuarine marsh habitats, threats to the harvest of wild shellfish and the shellfish aquaculture industry, the Dungeness crab fishery, salmon recovery and a complex array of ecological impacts to food webs,” Fish and Wildlife officials said.
According to WDFW, there have been dramatic impacts on species such as the small shore crab, clams and small oysters, especially in areas where the green crab has been able to reproduce significant populations.
A green crab can reportedly consume 40 half-inch clams in a day, as well as other crabs its own size.
According to WDFW, there are native green grabs in the Pacific Northwest that can be confused with European green crabs.
Officials said green crabs can turn red as they age, which causes confusion if one does not have a trained eye to distinguish between them.
“In Washington state, the European green crab is most often confused with native helmet crab or hairy shore crab,” WDFW said.
Characteristics of a European green crab:
Spines
- The most distinctive feature of the European green crab is not its color — which can vary from reddish to a dark, mottled green — but the five spines or teeth on each side of the shell. This number of spines is different from any other crab you are likely to see on the beach.
Size
- At its largest, the back shell (carapace) measures up to four inches across, but it is more common to find smaller, younger crabs. Males are generally larger than females of the same age.
Color
- Although known by the common name of green crab, color is not its distinguishing feature. Juvenile crabs can change their shell color to match their surroundings each time they molt. Adults are usually dark-greenish with yellow markings, and often have some orange at the joints. The underside of the crab is off-white, but can sometimes be bright yellow or even red.
Shape
- The back shell (carapace) is wider at the front than the back. The best way to distinguish the green crab from other species is by the number of spines next to the eye (marginal teeth). The green crab is entirely distinct from other native crabs, with its five marginal teeth.
Legs and claws
- The green crab has relatively long legs compared to the main body, and narrow claws. The last pair of legs is slightly flattened.
The European green crab was discovered on the state’s coast in 1998 in Willapa Bay and Grays Harbor, and later in other areas.
The crab first arrived in the U.S. in the mid-1800s, arriving by ship to the Cape Cod region.
WDFW currently is not asking for the public to kill the invasive green crabs, as it hops to protect native crabs from cases of mistaken identity.
“It might be hard to let a crab go when you are concerned it could be invasive, but keep in mind that WDFW will respond to any confirmed sightings quickly, and the best thing you can do is to get the information to us as soon as possible.”
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